Five loud explosions shook the center of Libya's capital Thursday afternoon, possibly striking near Moammar Gadhafi's compound in Tripoli, as rebels in the western mountains claimed control of the Zawiya oil refinery.

The thunderous blasts rattled a hotel where journalists stay in Tripoli. Gadhafi's compound is near the hotel and a frequent target of air raids.

NATO jets flew overhead minutes after the blasts. It wasn't immediately clear what was hit or if there were civilian casualties.

NATO has bombarded military targets all over Libya since March when a no-fly zone was instituted.

About 30 miles west of Tripoli, rebel fighters clashed in the city of Zawiya and took over the refinery there.

"We have full control over the Zawiya oil refinery and we have liberated the whole city except two main streets," Col. Ali Ahrash told The Associated Press.

Gadhafi troops were still in control of Gamal Abdel-Nasser Street and were hiding in the hospital there, he said. Ahrash said Omar Mokhtar Street was still under Gadhafi forces control and that a few more troops were patrolling in eastern Zawiya.

Since the rebels entered Zawiya last week - their most dramatic advance yet after months of stalemate - Gadhafi's troops have been pounding homes, mosques and streets with rockets and mortar fire.

Ahrash was in Benghazi on a mission when he spoke to the AP.

"In the past three days we have lost 70 fighters and more than 55 were injured," he said.

He said rebels have control of the cities of Surman, Sabratha and Zwara, as well as the road to Tunisia from Tripoli.

Libya's civil war began in February, with the rebels quickly wresting control of much of the eastern half of the country, as well as pockets in the west.

The conflict later settled into a stalemate with the rebels failing to budge the front lines in the east since April.

However, in recent weeks, rebels based in the western Nafusa mountains have advanced toward Gadhafi-held towns along the coast.

The capture of the 120,000-barrel-per-day refinery in Zawiya is more a symbolic coup for the rebels, without having a major impact on Gadhafi's ability to secure fuel.

The flow of crude to the refinery from fields in the southwest of Libya had largely been halted since midsummer. The refinery was believed to be running at about one-third of its normal capacity, drawing mainly on crude oil that was in its storage tanks. Zawiya mostly produced fuel oil, not gasoline.

Back in Tripoli, Prime Minister al-Baghdadi Ali al-Mahmoudi said the government was in negotiations with rebels.

"We are also calling on all sides for a cease-fire," al-Mahmoudi said.

Gadhafi's government has previously called for a cease-fire, but continued to bomb towns where rebels tried to take power.

On a second front, hundreds of miles from Zawiya around the coastal town of Brega, rebels clashed with Gadhafi troops for control of that town's refinery.

Rebels control the two residential units in the oil terminal but have spent almost a week fighting for the refinery.

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Hatoum reported from Tripoli, Libya. Also contributing to this report were Rami al-Shaheibi in Benghazi and Hadeel al-Shalchi in Cairo.